I flew C-130's (as Navigator) at Pope for 15 years. Our local lore was that the four northern drop zones (Sicily, Normandy, Solareno and Holland) were such big, hot sand boxes that they spawned their own thunderstorms. I was just watching the 1 hour radar loop and it appear that is happening this afternoon.

MIKE MOSS SAYS:     Coleman,      You were probably at Pope more recently, but who knows, maybe I briefed your crew sometime when I was  a Wing Weather Officer there!  You make a good point in that the mostly bare clay/sand surface of some of those DZs probably enhances convection relative to surroundings, and may act as a local trigger for shower and storm initiation. We noted this as a potential factor in our local area and DZ forecasts when I was there, but also noted that many other variables affect the formation, intensity and movement of storms in the area, enough that it could be difficult to isolate the differential heating effects associated with those zones. For example, on hot days a "Piedmont Trough" can form and serve as a focal point crossing through the same general area at times, and there are soil and vegetation contrasts across the Sandhills to Coastal Plain transition zone that play a role as well. To tease out a confident (and reasonably consistent) relationship between the DZs and convective storms might be possible, but would take a lot of detailed data and time - might make a good thesis project for an enterprising grad student! In the case you cited from July 7th, the cell that formed in the vicinity of the DZs was accompanied almost simultaneously by cell growth over parts of Moore, Bladen and Duplin counties, indicative of a supportive environment for isolated to widely scattered storms that didn't necessarily depend on terrain triggers as large and notable as the drop zones.